The transition from a classical to a quantum world as a passage from extensive to non-extensive thermodynamics

We study the thermodynamical properties of the quantum kicked rotator, coarsened by an external fluctuation with a weak intensity D, by means of the Tsallis entropy with a changing entropic index q. The genuine entropic index, corresponding to given values of D and $\hbar$ is that making the Tsallis entropy increase linearly in time, and it is proved to become q <1 for suitably large values of $\hbar$: This indicates a subdiffusional regime which, in turn, signals the occurrence of quantum localization. Thus the process of Anderson localization is shown to be compatible with a thermodynamical representation provided that a non-extensive form of entropy is used.